Control device



June 29, 1965 K, w, KERN, JR 3,191,624

CONTROL DEVICE Filed Jan. 4. 1962 Il nl 23\ 25N 65D e/27' /ZI 2? I5 (99! 3| /23 /l3 2' l ATTORNEY United States Patent C) 3,191,624 CONTROL DEVICE Karl William Kern, Jr., Dayton, Ohio, assignor, by mesne assignments, to E. E. Sandifar, Springfield, Ohio Filed Jan. 4, 1962, Ser. No. 165,063 8 Claims. (Cl. IS7-625.6)

This invention relates to a control device. More particularly, it relates to a control valve for regulating the upper limit of the pressure of a system by automatically providing communication of the pressure supply means of said system with a discharge passage when the pressure of the system reaches a selected value.

The control device described herein lis particularly useful where it is desired to control or limit the maximum pressure of a pressurized system. It is especially useful in hydraulic systems such as the hydraulic hoist unit of trucks and similar vehicles or hoists such as those used in service stations.

The control valve is placed inthe pressure line between the pressure supply means such as a hydraulic pump and the pressurized system. In the past, the usual means for controlling the maximum pressure of such systems as hoists, has been to install a pop-olf valve in the system so that when the pressure of the system reaches a maximum allowable value the valve opens to relieve the pressure and prevent it from getting higher. One disadvantage of this type of pressure relief device is that the pressure supply means must work at the maximum pressure if the system pressure is to be maintained at maximum value.

When the control valve of this invention is used to control the maximum pressure of a system and after the maximum system pressure has been reached, the relief valve maintains the maximum pressure and the pump or pressure supply means can be relieved to operate against a much lower pressure. In hydraulic lifts that are Working constantly, and where it is desirable to keep the pressurizing means operating at all times, this invention increases the life of the pressure pump considerably since the pressure pump need not work at maximum load constantly. In conventional apparatus where a pop-olf valve is used, the pump must work against the high pressure or maximum load during the time that the lift or hoist is maintained at its uppermost or top position.

When a lift or hoist reaches top position and can go no further, the pressure used to drive the hoist builds up until some relief is provided. The control valve of this invention lprovides the necessary shift of pressure flow to the hydraulic pump when the hoist reaches the top position, but sustains the presure in the hoist system that is necessary to maintain the hoist at top position. Although the control valve can be used for many purposes, the following description, for convenience, refers to the valve as being used for a hoist.

In the drawings:

FIG. l is a cross-sectional elevational view of a control and relief valve according to this invention with the plunger of the valve positioned to raise the hoist.

FIG. 2 is a cross-sectional elevational view of the control and relief valve with the plunger positioned to maintain the position of the hoist.

FIG. 3 is a cross-sectional elevational view of the valve of this invention with the plunger positioned to lower the hoist.

FIG. 4 is a diagrammatic view of a typical linkage suitable for use with the valve of FIGS. l-3.

Referring to FIGS. 1, 2, and 3, the control valve 11 has a valve body divided conveniently into a pilot head .13, a main body .15, a front head ,17, and a sub plate 1,9. A central bore 21 passes through the front head ICE 17, and the main body 15, and ends in the pilot head 13. Sealing means such as gaskets 23-23 are positioned between the various body members to Iprevent leakage of iiuid. A plurality of chambers are provided, surrounding the central bore, and preferably include a tank chamber 25, a system chamber 27, an inlet chamber 29, and a discharge chamber 31.

A plunger 33 is reciprocally movable in the central bore 21, and includes a plurality of pistons preferably a head piston 35, a valve piston 37, and a pilot piston 41. A pilot chamber 43 is provided at the right end of the central bore 21 in the pilot head 13. At the left end of the central bore 21 a seal 45 is provided to prevent dust and dirt from entering and collecting in the central bore 21. A small vent 48 allows the air to enter and exit from the central bore 21 during reciprocation of the head piston 35. A more positive seal -is provided on the head piston 35 such as a groove 47 containing an O ring 49. The valve piston 37 subdivides the plunger 33 into a rst plunger section 51 and a second plunger section 53.

A pressure supply means such as a positive displacement pump (not shown) supplies the working fluid to the control and relief valve 11 through an inlet port 55. The inlet port 55 communcates with an inlet valve chamber 57 containing a check valve 58 comprising a ball 59, a spring 61, and a valve seat 63. When the plunger 33 is in the position as shown in FIG. l, the iluid enters the -inlet chamber 29 passes along the plunger portion 51 within the valve bore 21 and enters the system charnber 27. Access of the iluid to other portions of the bore is blocked by the valve piston 37 and the head piston 35. The iiuid passes from the system chamber 27 through a system port 65 which is preferably threaded to receive the system pressure line (not shown).

The pressurized uid is supplied to the system until the pressure therein reaches a selected pressure. A second check valve 67 is provided which is sensitive to, and opens at, the selected pressure. The adjustable pressure check valve 67 preferably comprises a ball 69, a seat 71, a ball carrier 73, a spring 75, a seal 77, a plug 79, and an adjustable screw 81. The aforementioned parts of the valve 67 are` positioned in a valve chamber 83. A short communication passage connects the inlet valve chamber 57 with the valve chamber 83. The force of the spring 75 is adjustable by moving the adjustable screw 81 to compress or lengthen the spring 75. Once a pressure Ahas been selected by adjusting the screw 81, the response level of the valve 69 may be fixed by tightening a lock nut 87 to hold the adjustable screw 81 in position. I

When the uid pressure has reached the selected pressure level, the valve 67 is forced open and Huid enters the valve chamber 83. From the valve chamber 83, the i iiuid passes through the pilot port 89 located at the right end of the chamber 83 and into the pilot chamber 43. As is apparent in FIG. l, the diameter of the pilot chamber 43 is larger than that of the pilot piston 41, providing an annular space around the pilot piston 41 through which fluid can iiow into and out of the pilot chamber 43 via the pilot port 89. e

After the iluid enters and lls the pilot chamber 43, it passes through a plunger conduit 90. The plunger conduit 90 extends into the head piston 35 and communicates with flats A91--91 `on the external surface of the head piston through a plurality of radial passages 93. With the plunger 33 in the position of FIGL l, the flats 91 provide a space between the head piston 35 and the central bore 21, and this space is just short of communicating with the tank chamber 25. As the iiuid lls up and the pressure builds up inthe pilot chamber 43, the plunger 33 is moved toward the open (left) end of the bore 21. The valve piston 37 begins to move so as to close oli the communication between the inlet chamber 29 and the system chamber 27.

In the meantime, the space produced by the flats 911-91 on the head piston 35 communicates with the tank chamber and iiuid passes into the tank chamber 2S and further into tank 917 and out through the outlet port 103 to a sump (not shown). The system pressure is now stabilized, and the pressure continues to build up in the inlet chamber 29, the valve chamber 83, and the pilot chamber 43. The pressurebuilds up in the pilot chamber- 43 because the flats 91-91 are sized small enough that the iiuid does not escape rapidly enough from the pilot chamber 43 to avoid the pressure build up, but merely enough to keep the pressure from becoming excessive and to smooth out the movement of the plunger 33. A further build up of pressure by the pressure supply means continues to force the plunger 33 toward the left end of the central bore 21 until the inlet chamber v29 communicates withf the discharge chamber 31, as shown in FIG. 2.

The iiuid can now pass along the plunger portion 53 into the discharge chamber 311. A discharge port 99 is provided to `allow the fluid to pass from the discharge chamber 31 to a sump, waste tank, or other means (not shown) allowing the pressure on the pressure supply means to vbe relieved. As the plunger 33 moves further to the left, the radial passages 93-93 eventually communicate directly with the tank chamber 25 so that the pressure in the pilot chamber is relieved and the plunger 33 stops moving to the left. As soon as the pressure of the pressure supply means is relieved by communication of the inlet port 55 and discharge port 99, the valve 67 closes, and no more fluid passes into the pilot chamber 43. A threaded left end portion 161 is provided on the plunger 33 to engage any desired linkage, preferably having conventional detent or stop means, so that the plunger is maintained in the position of FIG. 2. A typical linkage 211i for this purpose is shown diagrammatically in FIG. 4. A handle 211 is used by the operator to adjust the position of a control lever 212, which is pivotably connected at 213 to a ixed base 214. The control lever 212 is pivotably connectedV at 215 to a rod 216 which is fixedly attached to the threaded left end portion 101 of theV plunger 33 (FIGS. 1-3). A substantially hemispherical inward projection 217 at the lower end of the control lever 212 Iesiliently engages a similarly shaped detent 1, 2, or 3 to maintain the plunger 33 in the position shown in the correspondingly numbered FIG. l, 2, or 3 when placed in such position by the operator or when moved to the position of FIG. 2 by the action of the control valve 11 as described above.

When the operator of the hoist wishes to lower the system pressure or drop the hoist, he moves the plunger 33 by the control lever 212 or other conventional means to the position shown in FIG. 3. As is` apparent from FIGS. 2 and 3, communication is maintained between the inlet port 55 and the discharge port-99. As the plunger 33 is moved from the position of FIG. 2 tov the position of FIG. 3, the system pressure is reduced, lowering the hoist by establishing communication between the system port 65 and the tank 97.

turned again to the position of FIG. 1 to continue raising whatever load is on the hoist. Simple mechanical means, such as the linkage `210 yof FIG. 4, may be proi? vided at the threaded end 101 to mechanically maintain the plunger in the various positions of FIGS. 1, 2, and 3 for intermediate operation between the top and bottom positions of the hydraulic lift.

While the form of the invention herein disclosed constitutes a preferred embodiment, it is not intended to describe all of the possible equivalent forms or ramiiications of the invention. It will be understood that the words used herein are terms of description rather than of limitation, and that various changes may be made without departing from the spirit or scope of the invention.

What is claimed is:

1. A control device for a liuid system comprising:

(a) abody;

(b) a plunger reciprocable therein;

(c) means for moving said plunger in one direction in response to a predetermined pressure in said fluid lsystem from a iirst position to a second position;

(d) means for moving said plunger by external control from said second position to a third position, from said third position to said second and rst positions, and from said first position to said second position; and

(e) means on said plunger positioned to establish communication between said iluid system and a source of pressurized uid at said first position, between said source of pressurized iluid and a sump at said second position, and between said sump and said source of pressurized iluid and between said sump and said uid system at said third position.

2. A control device for a fluid system comprising:

(a) a body having a bore and a plurality of ports communicating with said bore, said ports including an inlet port connected to a source of fluid under pressure, a system port connected to said uid system, and first and second discharge ports connected to at least one .sump for the system fluid;

(b) a plunger reciprocable in said bore and dening a plurality of passages; means for moving said plunger by external force to a iirst position where said passages establish communication between said Y inlet and system ports; means for moving said plunger by a predetermined pressure of the fluid in saidV fluid system and by said external force to a second position where said passages establish comvmunication between said inlet and irst discharge ports; and means for moving said plunger by said external force to a third position Where said passages establish communication between said inlet and iirst discharge ports and between said system and second discharge ports.

3. A control device for a iiuid system comprising:

' (la) -a body having a bore and a plurality of ports communicating with Vsaid bore, said ports including an inlet port, a system port, a first disch-arge port and ,a second discharge port;

(b) a plunger reciprocable in said bore and having regions of reduced diameter that in conjunction with said `bore define ya plurality of passages, said passages establishing communication between said inlet and system ports at `a first position of said plunger, between said inlet and tirs-t discharge ports at aV second position of said plunger, and between said inlet and r-st discharge por-ts and between saidsystem la-nd second discharge ports at a third position of said plunger; and

(c) means responsive to a predetermined pressure of the system iiuid for moving said plunger from said rst position to said second position.

4. A control device for .a fluid system comprising:

(a) a body having a bore therein open at one end and closed `at the opposite end anda plurality of ports communicating with said bore, said ports including an inlet port connected to a source of iluid under pressure,a system port connected toV said fluid system, and first .and second discharge ports connected to at least one sump for the system liu-id; l

(b) a plunger reciprocable in said bore to first, second, and third positions, said plunger defining first, second, and thi-rd passages, said first passage communicating with said inlet and system ports at sa-id first position of said plunger and with said system and second discharge ports at said third position of said plunger, said second passage communicating with sa-id inlet and first discharge ports at said second and third positions of said plunger, and said third passage communicating with the closed end of said bore and said second discharge port at said second position of said plunger; :and

(c) a pressure respon-sive valve between said inlet port and said closed end of said bore for allowing system `fiuid to move said plunger from said first position to said second position at a predetermined pressure of said fluid.

5. A cont-rol device for a fluid system comprising:

(a) a body having a bore, said bore h-aving a closed end;

(ib) la plurality of ports in said bore comprising an inlet port connected to a source of liu-id under pressure, a system por-t connected to .said fluid system, and first `and second discharge ports connected to at least one sump for system fluid;

(c) a plunger positioned in said bore with one end extending from said bore, said plunger being reciprocable in said bore and having regions of reduced diameter forming first, second, and third cavities between said plunger .and the wall of said bore, said iirst, second, and third cavities being reciprocable with said plunger;

(d) a pressure responsive valve positioned in a passage between said inlet port and the closed end of said bore, said pressure responsive valve opening at a predetermined pressure .to supply pressurized system fluid to the closed end of :said bore to move said plunger from a first position, where said inlet port communicates through said second cavi-ty with said' system port, to a second position, where said inlet port communicates through said irst cavity with said -irs-t discharge port;

(e) a passage through said plunger communicating with the closed end of said bore and said third cavity, said third cavity communicating with said second discharge port when `said plunger reaches said second position thereby relieving the pressure of the system fluid supplied .to the closed end of said bore through said pressure responsive valve .and thus stopping the movement of said plunger at said second position; and

(t) external means for moving said plunger to a third position, where said inlet port communicates through said first cavity with said first discharge port and where said system port communicates through said second cavity with s-aid second discharge port, said external means being further operable for moving said plunger to said first and second positions.

6.v A control device for hydraulic systems and the like,

comprising:

(a) ta body having 4a bore, said bore having a closed end and regions of enlarged diameter forming a plurality of chambers communicating with said bore; said plurality of chambers including a first kdischarge chamber, an inlet chamber, a system chamber, and a second discharge chamber;

(b) a plurali-ty of ports in said bore comprising an inlet port communicating with said inlet chamber :and connected to a source of fluid under pressure, .a system port communicating with said system chamber and connected to a hydraulic system, a first discharge port communicating with said first discharge passage and connected to a sump for hydraulic fluid, :and a second discharge port communicating with said second discharge passage and connected to a ysump for hydraulic fluid;

(c) `a plunger positioned in said bore with one end eX- tending from said bore and the opposite end forming Ia pilot chamber in conjunction with the closed end of said bore;

(d) regions of reduced diameter on said plunger forming first and second cavities between said plunger and the wall of said bore, said first and second cavities being reciprocable with said plunger;

(e) la plurality of flat regions on said plunger forming a plurality of hollows between said plunger and the wall of said bore, said hollows communicating with a plurality of channels radiating from the center of said plunger;

(if) a valve, adjustable to open at various pressures, positioned in a passage between said inlet port and said pilot chamber, said valve opening at a predetermined pressure to supply pressurized liuid to said pilot chamber to move said plunger from a irst position, where said inlet chamber communicates through said second cavity with said system chamber, to =a second position, where said inlet chamber communicates through said first cavity with said iirst discharge chamber;

(g) a passage through said plunger communicating with said pilot chamber and said plurality of channels radiating from the center -of said plunger and establishing communication with said second discharge passage .through said plu-rality of hollows when said plunger is .at said second position thereby relieving 'the pressure of the fluid in said pilot chambers and thus stopping movement of said plunger at said second position; and

(h) external means for moving said plunger to a third position, where said inlet chamber communicates through said i-rst cavity with said first discharge chamber and said system chamber communicates through said second cavity with said second discharge chamber, said external means being further operable for moving said plunger to said iirst and second positions.

7. A control device according to claim 6, said fiat regions being sized small enough to avoid rapid escape of fluid from said pilot chamber, permitting the pressure of said fluid to build up without becoming excessive, and smoothing out the movement of said plunger.

8. A control device according to claim 6, wherein said adjustable valve closes in response to the reduction of pressure in said inlet chamber when said plunger reaches said second position.

References Cited by the Examiner UNITED STATES PATENTS 2,448,532 9/48 Kirkham 137-596.12 XR 2,757,641 8/ 5 6 Meddock 137--62427 2,800,922 7/ 5 7 Charlson 137--62427 M. CARY NELSON, Primary Examiner. KARL J. ALBRECHT, Examiner. 

3. A CONTROL DEVICE FOR A FLUID SYSTEM COMPRISING: (A) A BODY HAVING A BORE AND A PLURALITY OF POSTS COMMUNICATING WITH SAID BORE, SAID PORTS INCLUDING AN INLET PORT, A SYSTEM PORT, A FIRST DISCAHARGE PORT AND A SECOND DISCHARGE PORT; (B) A PLUNGER RECIPROCABLE IN SAID BORE AND HAVING REGIONS OF REDUCED DIAMETER THAT IS CONJUNCTION WITH SAID BORE DEFINE A PLURALITY OF PASSAGES, SAID PASSAGES ESTABLISHING COMMUNICATION BETWEEN SAID INLET AND SYSTEM PORTS AT A FIRST POSITION OF SAID PLUNGER, BE- 